The Federal Communications Commission (FCC) has allotted a spectrum of bandwidth in the 60 GHz frequency range (57 to 64 GHz). The Wireless Gigabit Alliance (WiGig) is targeting the standardization of this frequency band that will support data transmission rates up to 7 Gbps. Integrated circuits, formed in semiconductor die, offer high frequency operation in this millimeter wavelength range of frequencies. Some of these integrated circuits utilize Complementary Metal Oxide Semiconductor (CMOS), Silicon-Germanium (SiGe) or GaAs (Gallium Arsenide) technology to form the dice in these designs.
CMOS (Complementary Metal Oxide Semiconductor) is the primary technology used to construct integrated circuits. N-channel transistors and P-channel transistors (MOS transistor) are used in this technology which deploys fine line technology to consistently reduce the channel length of the MOS transistors. Current channel lengths examples are 40 nm, the power supply of VDD equals 1.2V and the number of layers of metal levels can be 8 or more. This technology typically scales with technology and can achieve operation in the 60 GHz range.
Transceivers for the 60 GHz system have been formed in CMOS and comprise at least one transmitter and at least one receiver which are used to interface to other transceivers in a communication system. The transceivers receive or transmit electrical signals into the LNA or the power amplifier, respectively. These electrical signals are generated by or provided to an antenna. The antenna is a transducer that converts incoming electromagnetic energy from free space into electrical signals on the receive side of the transceiver or converts electrical signals into electromagnetic energy for transfer into free space.
Millimeter-wave integrated antennas for ultra-wide band (57-64 GHz band) applications need to have a low path loss, high antenna gain and large impedance bandwidth to provide sufficient link budget. Millimeter-wave integrated antennas had been well investigated in the past, such as tapered slot antennas (for example, see:), planar Yagi antennas (for example, see: R. A. Alhalabi and G. M. Rebeiz, “High-gain Yagi-Uda antennas for millimeter-wave switched-beam systems,” IEEE Trans. Antennas Propag., vol. 57, pp. 3672-3676, November 2009.), and dielectric rod antennas (for example, see: Takashi Ando, Junji Yamauchi, and Hisamatsu Nakano, “Numerical Analysis of a Dielectric Rod Antenna—Demonstration of the Discontinuity-Radiation Concept,” IEEE Trans. Antennas Propag., vol. 51, no. 8, pp. 2003-2007, AUGUST 2003.) for endfire radiation, or some of the more traditional patch or dipole antennas for broadside patterns. Normally, a high-gain millimeter-wave antenna can be a direct miniaturization of its lower frequency version. However, scaling integrated antennas where there are minimum trace width/gaps and vias pitch requirements on planar surfaces and substrate thickness requirements to support system weight considerations is difficult. For compact applications in portable units, the area allocated for antennas is rather small, further complicating the high-gain antenna design. Millimeter-wave integrated antennas also have resistive losses due to the skin effect. Other techniques are required to overcome these resistive losses and area resource allocations. In addition, the antenna must have a low return loss and be able to generate appreciable gain. A solution to overcome these problems is described.
Two additional critical design parameters of a millimeter-wave integrated antenna include power output and directionality. In the ultra-wide band (57-64 GHz band), the range of the transmitted signal is limited if the signal must be propagated uniformly from the antenna in comparison to having a highly directional antenna that focuses the output power in a particular direction. The focused power allows the transceiver to propagate the signals for a greater distance in a particular direction at the expense of reducing the signal transfer in other directions. This makes alignment between two transceivers more challenging. Several solutions are provided to overcome this shortcoming.